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This page is written by the game's inventor, David Howe.

Combination Chess

This game is intended as a submission for the 39-square contest.

Ok, I admit it, the board is not very interesting or clever. And the individual pieces aren't all that interesting either. However, the way they interact should be. This game features the three basic piece movements from orthodox chess (ie. the rook, bishop and knight). Two new pieces have been added which are unique to this game and effect the way pieces interact with each other.

The basic idea is that in addition to its movement abilities, each piece has a "zone of influence". Any friendly pieces that are in that zone acquire the movement and capture abilities of the influencing piece. So, if a rook was in the zone of influence of a bishop, the rook would essentially have the move of a queen.

This lets pieces interact in a more dynamic, combinatorial way than they normally do in chess. A move doesn't merely change the board position, it changes the abilities of the pieces in the locality of the moved piece also.

As usual, the rules of usual (or FIDE) chess apply except where noted below.

Note: After creating this game I doubled checked Hans' web site to make sure there wasn't already a game like this, but alas, there was (Dynamic Chess). I may have subconsiously been influenced by this game, even though I can't remember having read it.

Zones of Influence

Each piece (except pawns and kings) has a "zone of influence". Any friendly piece in this zone absorbs the inherent movement and capture abilities of the piece. The absorbed abilities are lost when the piece is no longer within the zone of influence. Zones of influence are marked with the pound sign (#) in the diagrams below.

King

The King never has a zone of influence. However, it may be influenced. Note that the King may never move through a square that is threatened by an opposing piece. There is no castling.

Pawn

Pawns never have a zone of influence. However they may be influenced. Pawns do not promote, nor do they have an initial two-square move.

Bishop

The bishop influences those friendly pieces in orthogonally adjacent squares. It moves and captures as a orthodox chess bishop. 
   +---+---+---+
   |   | # |   |
   +---+---+---+
   | # | B | # |
   +---+---+---+
   |   | # |   |
   +---+---+---+

Rook

The rook influences those friendly pieces in diagonally adjacent squares. It moves and captures as a orthodox chess rook. 
   +---+---+---+
   | # |   | # |
   +---+---+---+
   |   | R |   |
   +---+---+---+
   | # |   | # |
   +---+---+---+

Knight

The knight influences those friendly pieces that are a one square jump away in any of the four orthogonal directions. The knight's zone of influence is not blocked by a piece on an intervening square. It moves and captures as a orthodox chess knight. 
   +---+---+---+---+---+
   |   |   | # |   |   |
   +---+---+---+---+---+
   |   |   |   |   |   |
   +---+---+---+---+---+
   | # |   | N |   | # |
   +---+---+---+---+---+
   |   |   |   |   |   |
   +---+---+---+---+---+
   |   |   | # |   |   |
   +---+---+---+---+---+

Amplifier

The Amplifier not only gives any friendly piece under its influence its movement ability, it also gives that piece its influence zone. For example, a knight in the influence zone of an amplifier, would then be able to influence any piece adjacent to it, in addition to the four squares that knights can normally influence.

The Amplifier moves and captures by jumping one square in any orthogonal direction. The intervening square may contain a piece. The amplifier captures if it "lands on" an opposing piece.

Note: if an amplifier and an opposing isolator influence each other, annihilation occurs, and all pieces within either of the pieces' zones of influence are removed from the board, including the amplifier and isolator. It is illegal to make a move that would cause one's own king to be removed from the board. 

   +---+---+---+---+---+
   |   |   | x |   |   |
   +---+---+---+---+---+
   |   | # | # | # |   |
   +---+---+---+---+---+
   | x | # | A | # | x |
   +---+---+---+---+---+
   |   | # | # | # |   |
   +---+---+---+---+---+
   |   |   | x |   |   |
   +---+---+---+---+---+

Isolator

The Isolator gives any friendly piece under its influence its movement ability. Any opposing piece under its influence has no influence. An isolator has no effect on the opposing isolator.

The Isolator moves and captures by jumping one square in any orthogonal direction. The intervening square may contain a piece. The isolator captures if it "lands on" an opposing piece. 

   +---+---+---+---+---+
   |   |   | x |   |   |
   +---+---+---+---+---+
   |   | # | # | # |   |
   +---+---+---+---+---+
   | x | # | I | # | x |
   +---+---+---+---+---+
   |   | # | # | # |   |
   +---+---+---+---+---+
   |   |   | x |   |   |
   +---+---+---+---+---+

Example

In this example, the white pawn absorbs the abilities of the Knight, and the white Knight absorbs the abilities of the rook. The pawn however cannot move like a rook because it does not absorb abilities that were in turn absorbed by the influencing piece.

If the white pawn moves one square forward, it loses its Knight move, and does not gain the bishop move because the bishop is in the influence zone the of black isolator.

The black Knight, since it's within the zone of the black ampifier, influences the black rook, so the black rook can move like a Knight.

The white pawn could capture the black isolator, and would also lose the Knight move, but gain the bishop move (since the black isolator would no longer be isolating the white bishop). 

   +---+---+---+---+---+
   |   | r | n | a | i |
   +---+---+---+---+---+
   |   |   |   |   | B |
   +---+---+---+---+---+
   |   | N |   | P |   |
   +---+---+---+---+---+
   | R |   |   |   |   |
   +---+---+---+---+---+
   |   |   |   |   |   |
   +---+---+---+---+---+

Initial Setup

                +---+
9               | k |
        +---+---+---+---+---+
8       | i | b | a | n | r |
        +---+---+---+---+---+
7       | p |   | p |   | p |
        +---+---+---+---+---+
6       |   | p |   | p |   |
    +---+---+---+---+---+---+---+
5   |   |   |   |   |   |   |   |
    +---+---+---+---+---+---+---+
4       |   | P |   | P |   |
        +---+---+---+---+---+
3       | P |   | P |   | P |
        +---+---+---+---+---+
2       | I | B | A | N | R |
        +---+---+---+---+---+
1               | K |
                +---+
      a   b   c   d   e   f   g

Initial influences. The following list covers how the pieces are influenced at the start of the game. All listed pieces have their normal moves in addition to those listed. 

     king at d1 or d9: bishop or knight
 isolator at b2 or b8: bishop
   bishop at c2 or c8: isolator or knight
amplifier at d2 or d8: bishop or knight
   knight at e2 or e8: amplifier
     rook at f2 or f8: knight
     pawn at b3 or b7: isolator or bishop
     pawn at c4 or c6: nothing!
     pawn at d3 or d7: amplifier, knight or bishop!
     pawn at e4 or e6: knight
     pawn at f3 or f7: knight
Written by David Howe.
This game is a submission in the contest to design a chess variant on a board with 39 squares.
WWW page created: October 5, 1998.
A simplified version of combination chess can be played with the Zillions of Games program. To play this game if you have this program, download the necessary files. (Zipfile.)